The present invention is directed generally to electronic control circuits for fluid dispensers and more particularly to an electronic reset circuit for resetting the meter of an automotive fuel pump.
Conventional automotive fuel dispensers or fuel pumps generally include a fuel pump and a meter for indicating the amount of fuel dispensed and the dollar amount of the transaction. The meter component is generally referred to as a "computer", although it may be a mechanically operated device as well as an electronically operated device. In most installations, the meter or computer must be reset to zero following shut-off of the fuel pump at the end of a transaction, before the fuel pump may be restarted for a subsequent transaction. In "full service" installations, this resetting presents little problem since the pump is always operated only by an attendant, rather than by the customer.
However, with the increasing popularity of "self service" installations, it is important to maintain control of the resetting of the meter to prevent a second customer from using the pump before the first customer has paid the indicated amount. In this regard it is not unheard of for a single customer to pump a given amount of fuel, reset the meter to zero and begin pumping again, thus paying only for the portion of fuel pumped after resetting.
The prior art has provided mechanical interlocking devices, however, problems have arisen with this approach. Commonly, such a mechanical interlock comprises a bar or like mechanical stop component which provides a stop for the pump handle and comes into play each time the pump handle is moved from its "on" position to its "off" position, preventing the handle from being again moved to its "on" position until an attendant has released the mechanical interlock. However, many customers are unaware of the existence of this mechanical interlock and hence are inclined to utilize an undue amount of force in an attempt to move the pump handle to its "on" position. This has frequently resulted in damage to either the mechanical interlock system or the pump handle itself, necessitating shutdown of the affected pump and relatively expensive and time-consuming repair.
The present invention therefore proposes an electronic reset control arrangement which avoids the problems encountered with the mechanical interlocking system. With the electronic reset system of the invention, the pump handle is at all times free to move, although movement thereof to the "on" position in the absence of actuation by the attendant of the electronic resetting system of the invention, will not reset the meter or permit fuel to be pumped. Hence, the customer may actuate the pump handle any number of times in the normal fashion in attempting to obtain service without causing any mechanical damage to the pump.
Providing an electronic resetting arrangement has heretofore presented at least two problems which the present invention solves. Firstly, the known hazards of using electrical circuits within or near areas of a gasoline dispenser wherein volatile fumes may be present must be overcome. Secondly, an electronic reset device should be capable of installation upon fuel dispensers of a number of different types, while remaining relatively easy to install and requiring little or no modification to the fuel pump or dispenser itself.